Georges River and Woronora River

We often talk about the Georges River catchment. A catchment is a land area where water is collected that feeds into a river. The catchment area for the Georges River is large, covering a landmass of approximately 1,000 square kilometres. Sometimes these catchment areas may not seem close to a river, but rainfall that occurs in these areas can feed into the flood effects of that river. Many people are not aware that they live in a catchment and that these areas are also impacted by floods directly or indirectly.

The Georges River itself is situated in Sydney's south and is approximately 100 kilometres long. The river flows through Liverpool, Chipping Norton Lake Scheme and then flows east through Bankstown and out to Botany Bay. This includes along the Local Government Areas (LGAs) of Bayside, Canterbury-Bankstown, Camden, Campbelltown, Cumberland, Fairfield, Georges River, Liverpool, Sutherland and Wollondilly. 

The Georges River is one of the most populated catchments in Australia, with approximately a quarter of Sydney’s inhabitants located here. There is a rich diversity of community, business and recreation areas in this location, attracting many people from outside the area. It is also known as one of the most severely flood prone areas in NSW. 

It is important to be aware of and understand the flood risks in this area. It is also important to know what to do when the Georges River does flood.

These pages can help you understand the risk and give you information on what to do before, during and after floods. There are also resources and further information for you to explore.

For a more detailed explanation on how the Georges River was formed, visit the Georges Riverkeeper website - What shaped the Georges River?

The Georges River has a long history of flooding. Not all of the historical floods on the Georges River have been the same. In fact, even though flood extents can be modelled, floods can be different every time. On the Georges River, flooding does not occur in any form of sequence as flooding can happen quickly and at the same time across different locations along the river.

Even higher floods than what has happened before can occur, impacting many residents, businesses and travellers to the area.

The main floodplain for the Georges River is between Glenfield and East Hills in Liverpool, Fairfield and Canterbury-Bankstown Local Government Areas.  There are different influences across the Georges River catchment in these areas. Flooding is fairly unique on the Georges River as the lower reaches of the river (from East Hills downstream) is confined to a narrow gorge which acts as a restriction during large floods. A further small gorge towards the outlet of the river creates additional adverse effects on flooding, as water cannot disperse quickly. Effects from these gorges results in a wide variety of flood inundation heights, depths and flow speeds across different locations along the river and in flood impacted areas. The only outlet for floodwater on the Georges River is through Botany Bay.  

Different weather systems can cause flooding on the Georges River, including what is known as an East Coast Low. East Coast Lows can deliver heavy rainfall across the catchment area, causing overland flow, flash flooding and waterways to break their banks, including for the Georges River and other creeks and tributaries which flow into the River. The extent of flooding is influenced by the intensity and/or duration of this rainfall.  Tidal levels can also contribute to the extent of flooding along parts of the Georges River. 

This is why it is important to be aware of flooding in areas you live, work and visit. 

The Georges River has several major tributaries that influence flood behaviour in the valley, including:  

• Bunbury Curran Creek
• Cabramatta Creek
• Prospect Creek
• Harris and Williams Creeks
• Salt Pan Creek and
• Woronora River

Local Councils do flood studies to determine the risks and the NSW SES write Flood Plans based on these studies. There is currently work being done to combine these pieces of work and create a catchment wide Flood Plan for the Georges River.

The Georges River has flooded before. It will happen again.

Visit the Georges Riverkeeper website for more information on floods on the Georges River.

The Georges River has a long history of flooding.

During the late 1800’s, records indicate significantly large events which caused great concern within the area. This saw the community within the floodplain experience a large number of minor, moderate and major flood events including a flood with a 1% chance happening every year (1 in 100-year flood event), which was recorded in 1873. This flood saw water heights rise above 10 metres with homes reported to have been washed away in the current.

Smaller recorded flood events occurred during the early 1800’s.

The largest flood on record over the last 100 years was the 1956 flood, when over 300 mm of rain fell across three days in the Georges River catchment. This resulted in the flooding of 1,000 homes and the evacuation of 8,000 people. Reports describe people being rescued from rooftops of homes, climbing there because of the rapidly rising floodwater. This flood is relatively small compared to other historical floods that have occurred.

Other large floods have been recorded during the 1900’s particularly in 1986, when over 320 mm of rain fell in a 24 hour period (the usual annual rainfall in the area is roughly in the vicinity of 870mm). This resulted in 6 deaths and 10,000 homes being damaged.

Larger floods are possible on the Georges River. It is not a question of if, but when these will happen.

Visit the Georges Riverkeeper website for more information on floods on the Georges River.

Meet Washington and Nancy, local NSW SES unit members. Residents and businesses along the Georges River need to know their flood risk and have a plan. Just a little preparation can save lives. Take your first step to get prepared.

Meet Hiendat, a local NSW SES unit member. The Georges River has a long history of flooding. Residents and businesses need to know how to stay informed and when to act. Flooding will happen again. That’s a fact. 

Meet Criss, a local community member from southwest Sydney. All communities living and working along the Georges River, need to know their flood risk. This can save your life and the lives of your loved ones. Find out about your flood risk and how to share this in your language.

Meet Jenny, a local business owner in southwest Sydney. Businesses can take simple steps to get prepared and have a plan. The Georges River will flood again. That’s a fact. Find out more on how a little preparation can protect your business and livelihood.

Meet Annie, a local resident living on the Georges River. Floods on the Georges River can happen quickly. Know the warning signs for floods and act early to keep you and your family safe. The Georges River will flood again. That’s a fact. Find out more on how to prepare your home for flooding.

The Woronora River rises on the north-western slopes of the Illawarra mountain range and has its origin from Waratah Rivulet, near Darkes Forest. The river flows generally north for approximately 36 kilometres, joined by three main tributaries, before reaching the Georges River, between Como and Illawong. The total catchment area of the river is approximately 174 square kilometres.

The Woronora Dam is a major feature of the catchment area. The Dam provides drinking water for the Sutherland Shire and some surrounding suburbs. Downstream of the dam the river passes through sandstone gorge terrain with the majority of the 95 square kilometres covered in Eucalypt forest. There is increasing urban development along the catchment ridgelines. There is residential development along the banks and floodplain of the final 11 kilometres of the Woronora River before it joins the Georges River near Como Bridge.

The Woronora River is a perennial river, meaning it has a continuous flow of surface water throughout the year during seasons of normal rainfall. It is also a tidal river, meaning that ocean tides can also affect the flow and height of river levels.

 Suburbs and locations along the Woronora River include:

• Woronora
• Woronora Heights
• Barden Ridge
• Como
• Menai
• Bangor
• Bonnet Bay
• Illawong
• Deepwater Estate

The Woronora River is a pristine waterway traversing through deep valleys and peaceful surroundings. It is a place of great beauty offering boating, canoeing, kayaking, swimming and fishing, with plenty of opportunity to stop off for a picnic and bushwalking.

The Woronora Valley is an area of great natural beauty and regional significance. The valley is home to several endangered ecological communities, threatened species and a diverse range of vegetation types including wetlands, saltmarsh, woodlands, forests, and heath.

The Woronora River has a long history of flooding. Significant floods have occurred on the Woronora River since the 1930's, with flood events in recent decades being in 2000, 2012, 2013, 2016, 2020 and the highest being in July 2022. Significant floods will happen along the Woronora River again and may even be greater than those experienced or behave differently than those in the past.

Data from flood studies have been used to create flood intelligence for the Woronora River. This includes modelled flood possibilities and data from historical floods. The collection of flood data and intelligence is a continual process through community feedback, flood modelling and assessing actual floods. 

It is important to understand the local risks, consequences and timings to act on Warnings issued by the NSW SES to ensure your safety and the safety of your family, households, friends, neighbours, pets, and businesses.

Visit the Sutherland Shire Council Website for local information on flooding along the Woronora River.

The collection of flood data and intelligence for Woronora River is an ongoing process through community feedback, flood modelling and damage assessment after actual flood events. Flood studies that model flood behaviour in simulated weather scenarios and recorded observations of historical floods are used to develop and refine local flood intelligence to consider possible impacts of flooding on communities along the river.

It is important to understand the local risks, consequences, and timings to act on Warnings issued by the NSW SES to ensure your safety and the safety of your family, households, friends, neighbours, pets, and businesses.

Rapid and dangerous river rises can happen on the Woronora River with some areas being susceptible to inundation and requiring evacuation for the safety of the local community. As isolation is also possible when significant roads are cut by floodwaters or if major utilities are impacted, earlier evacuation may be required. It is better to move people safely and avoid being cut off without power, water, sewerage, and other essentials. Travelling on a flooded river is dangerous and rescue may not be an option as it may be unsafe for NSW SES volunteers to launch flood boats.

It is important to monitor all warnings issued by the Bureau of Meteorology and the NSW SES for the Woronora River and follow the advice in these warnings. Decisions to release warnings are based on the protection of life.

• Monitor Woronora river heights at the Woronora River Gauge (Woronora Bridge)
• Monitor Woronora river heights at the Woronora River at the Needles
• Monitor Woronora river heights the Woronora River Woronora Dam

Images from the Bureau of Meteorology Woronora Bridge Gauge (July 2022):

Radio stations that may broadcast local warnings:

• ABC 702
• 2SSR
• Most commercial radio stations across Sydney

Sutherland Shire Council provides local information on flood prone land along the Woronora River in the planning/zoning layer of their Shire Maps Sutherland Shire Council.

Though most areas are subject to some flash flooding in heavy rains and tidal impacts are common along the foreshore, riverine flooding that could cause extended inundation or isolation is predominantly around low-lying areas of the river in Woronora and Bonnet Bay.

As flood intelligence is updated and made publicly available, the NSW SES will identify the specific communities at risk in the area.

The NSW SES Disaster Awareness Survey is a generic survey used in many locations across NSW. The survey measures impact of a campaign and/or engagement delivery in an area that focuses on raising community levels of awareness, knowledge and actions about flood, over time. Community responses to the surveys will help measure how effective the campaign has been.

The Woronora River Disaster Awareness Survey targets people who live and work in local areas along the Woronora River, particularly:

• Woronora
• Deepwater Estate

and waterfront areas of:

• Barden Ridge
• Bonnet Bay
• Como
• Illawong
• Shackle’s Estate

There are three surveys that aim to measure an initial level of awareness, knowledge and, actions and then compare these to later results from the following two surveys, one just after the engagement activities and the last one six months later to test for maintenance of levels.

NSW SES respects the privacy of people (Privacy Statement) and there are some answers to Frequently Asked Questions (FAQs) about the surveys once you begin the survey online.

NSW SES values the opinions of children and young people. For this reason, we require children and young people under the age of 18 to get the consent of a parent or guardian before they participate in a survey.

Responses will help measure the success of the campaigns, but they will also provide information on how the NSW SES can best direct preparedness community engagement work in these areas in the future, to build and support local resilience.

The initial survey will be promoted locally. Respondents who give their email details, will receive the follow-up surveys.

Overall results will be published on social media once the third survey has closed.

NSW SES have completed survey 1 in the Woronora River Flood Awareness Project.

The survey looked at local awareness and knowledge ratings and actions needed to be done and actions done to prepare for floods.

Subsequent surveys will be used to measure against these results to determine shifts in awareness, knowledge and actions for communities along the Woronora River.

60 surveys were completed, with 57 being from the targeted areas.

The overall average across flood awareness and knowledge was a rating of 3.64 out of 5

Levels of awareness had an average of 3.54

Levels of knowledge has an average of 3.78

These overall ratings show that flood awareness and knowledge are high in areas along the Woronora River.

Increasing the knowledge of local flood impacts and consequences will be important to grow this average

Engagement activities will focus on awareness and local flood knowledge as well as the Australian Warning System and how this relates to local flood consequences.

Local flood information is important to include in engagement activities to increase local flood risk awareness, including:

• Flood impact and consequence information
• River heights and local impacts on roads, houses and other infrastructure
• Historic flood information
• Flood impacts from Woronora Dam and Georges River
• Modelled floods, flood study information and Probable Maximum Flood

Almost 50% of respondents will wait for a warning and then follow advice.

Knowing the Australian Warning System and creating a Watch Zone are key messages to engage with communities along the Woronora River.

Just over 20% indicate that they would stay in place regardless.

Larger floods are possible. Staying is risking lives.

61% will act on warnings or act early.

37% would stay or rely on being told or others moving, before moving.

1/3 of people in the target locations need messages about acting early.

Comparison of Actions Needed and Actions Done

Areas of focus for further engagement are making an emergency plan for floods based on local flood information including:

• Indicate evacuation routes and when access to these will be open
• When local roads will be closed
• List key contacts (family, neighbours, schools, etc)
• Plan for your pets

Linking local flood plans NSW SES warnings (create a Watch Zone), identify triggers for action, including:

• When to enact your plan
• When to secure items that may float and cause damage
• When to move items to higher ground
• When to ready for evacuation
• When to evacuate

WaterNSW are responsible for flood operations at Woronora Dam and provide real-time advice for the public to opt-in to through their Early Warning Network.

The move to the AWS is exciting as it significantly improves the way NSW SES warn communities along the Woronora River during floods.

This is especially important for communities along the Woronora River as some community members follow an old colour-coding system adopted in 1998 (from the Woronora Floodplain Management Study or Flood Education Strategy), to interpret and understand flood risk. The new warning system, along with NSW SES Planning processes, supersedes this old system.

The improved way of having consistent warnings directly links to triggers that have been refined and updated to include intelligence and feedback. This is important as it has been applied to local emergency management sectors to create the adequate sequence of warnings for communities. This accounts for those changes seen since the previous study.

It is important for communities to understand how to use these tools and warnings to support making informed decisions when it floods.

Locations along the Woronora River will receive a sequence of targeted Warnings specific to the local impacts of flooding.